1. Field of the Invention
The present invention relates to a photosensitive material for the electrophotography. More particularly, the present invention relates to an improvement of a photosensitive material comprising a perylene type pigment dispersed in a polyvinyl carbazole type charge-transporting medium, in which a halogeno-p-benzoquinone is incorporated in this dispersion to increase the sensitivity of the photosensitive material and prevent the fatigue at the repeated exposure.
2. Description of the Prior Art
As the signal-layer type photosensitive material comprising a dispersion of a charge-generating pigment in a charge-transporting medium, there is known a photosensitive material comprising a phthalocyanine pigment or disazo pigment in a medium composed mainly of a polyvinyl carbazole resin, and it is known that a dispersion of a perylene type pigment in a polyvinyl carbazole resin (often referred to as "PVK" hereinafter) has no substantial sensitivity and it can hardly be put into practical use.
Furthermore, it is known that various sensitizing agents may be incorporated so as to sensitize photosensitive layers of the charge-transporting medium/charge-generating pigment dispersion type. However, when most of these sensitizing agents are incorporated in a PVK-perylene type pigment composition, no satisfactory results are obtain in the sensitivity, the charge potential or the repetition characteristics.
We found that a halonaphthoquinone has a substantially satisfactory sensitizing effect to the PVK-perylene pigment composition. However, a photosensitive material having the halonaphthoquinone incorporated therein is defective in that the fatigue at the repeated exposure, that is, the memory effect, is extreme and the initial saturation charge voltage on the surface of the photosensitive material is drastically reduced by repetition of the light exposure.